A post-eclosion early learning involved in host recognition by Dinarmus basalis rondani (Hymenoptera: Pteromalidae)

Host preference was induced during the early development of Dinarmus basalis, an ectoparasitoid of bruchid beetle larvae feeding inside bean seeds. A series of experiments at successive stages of the parasitoid's development showed that host-preference depends on a learning process that takes place after the eclosion of the adult parasitoid but before it emerges from the chamber beneath the bean's integument. During this period of a few hours the callow parasitoid may be affected by stimuli from the shrivelled remains of the host. The effect depends on the host species. Zabrotes subfasciatus provoked a change in host-preference but Acanthoscelides obtectus did not. Host-preference induction is strongly constrained, therefore, by factors endogenous to the parasitoid. This type of early learning appears to be novel in parasitoid wasps because of the time at which it occurs.